Water from the oceans and the seas is a potential source of fresh water, provided that it is desalted beforehand, by distillation. Solar energy has long been proposed as the source of energy therefor.
Actually the solar energy-driven evaporation of sea water leading to the formation of salt deposits and the condensation of evaporated water by cooling is the fundamental phenomenon which rain is based on.
The prior art literature describes a lot of conditions, in which evaporation of sea water and the subsequent condensation and collecting of the fresh water thus obtained could be achieved, at least theoretically.
The apparatus disclosed in the German Patent Application DE-A-2 830 705 involves the carrying out of the evaporation and the condensation in a single wing-shaped canal.
The Australian Patent AU-B-532266 described the desalting of sea or brackish water by using two adjacent parallel canals both fed by said sea or brackish water and one of which comprises a greenhouse structure, whereas the second one comprises an appropriate second structure for condensing the vaporized water and recovering the condensed water, said second structure being in fluid communication with said greenhouse-like structure and mostly immersed in the other of said two canals.
U.S. Pat. application No. 3,338,797 described a sophisticated apparatus for transforming saline water into fresh water by solar energy and for generating electrical power from said fresh water. Said apparatus should comprise:
several tanks, two of which are contiguous and comprise an open lattice work which serves as a support for a number of appropriately shaped blocks, useful for the condensation and collecting of the evaporated water, PA1 electro-mechanical means for conveying and pumping, PA1 a rotated screw used for moving salt from one tank upwardly to a salt box wherein said salt is discharged, and PA1 other means for conveying and collecting matters, equipped with appropriate valves and pumps. PA1 a rudimentary system for collecting of the evaporated water, also comprising means for an artificial warming up, and PA1 a chimney-like system, the purpose of which was to raise the water vapor up to a height where the condensation occurred and enable using for irrigating grounds downwards and producing electricity the water thus obtained by condensation at the top.
The German Patent Application DE-A-3 440 842 disclosed a device and a method which comprised:
There was still a need, therefore, for a device and a method for the production of fresh water by desalting sea or brackish water with a thorough control, under precise physical conditions and with a high efficiency, of the basic phenomena of evaporation and condensation, advantageously without any source other than the solar energy.